Active matrix/organic light-emitting diode (AMOLED) display is one of the research hotpots for a current flat-panel display device. The OLED has such advantages as low power consumption, low production cost, self-luminescence, wide viewing angle and rapid response. The design of a pixel driving circuit is a core of the AMOLED display, and thus it is of important research significance.
For the AMOLED display, it is required to provide a stable current to control the OLED to emit light. Due to the manufacturing process and the aging of devices, a threshold voltage (Vth) of a driving TFT for each pixel point will be drifted, which results in a change of the current passing through the OLED for each pixel point along with a change of the threshold voltage. As a result, the display brightness is uneven, and thereby a display effect of an entire image will be adversely affected.
Currently, an in-cell touch technology has been applied to a liquid crystal display (LCD). As the most difficult problem to be solved in the in-cell touch technology, there is signal interference, i.e., there is a considerable parasitic capacitance between a touch electrode and an electrode desired for the operation of the LCD. As a result, it is very difficult to prevent display characteristics of the LCD itself from being adversely affected while ensuring that a touch signal is collected successfully. Hence, a combination of the in-cell touch technology with the AMOLED will be a future trend of the display technology.